Teen boys' eating disorders may focus on muscle gain, not weight loss

Many people may mistakenly assume teen boys are not prone to eating disorders because their symptoms are different from what’s typically seen in girls and their focus is on building muscle rather than becoming impossibly thin, doctors warn.

What many parents and pediatricians consider classic symptoms of adolescent eating disorders, like calorie restriction and purging, are actually hallmarks of illness in girls, not boys, Dr. Jason Nagata of the University of California San Francisco and colleagues write in a commentary in the Lancet Child & Adolescent Health.

Screening for teen eating disorders for both sexes often focuses primarily on these symptoms that are more typical among girls, the authors note.

“Many assessment tools that are currently standard practice to diagnose eating disorders are geared towards females and are based on weight loss behaviours with the goal to become thin,” Nagata said by email.

As a result, pediatricians and parents may not notice eating disorders among teen boys, which are often characterized by eating too much protein, rigid restriction of carbs and fats, and cycling between periods of overconsumption and calorie cutting in an effort to build muscle, the doctors write. Boys with eating disorders may also use steroids or supplements to bulk up or may compulsively exercise.

“Exercise is an under-recognized component of eating disorders,” Nagata said. “Teenagers who excessively exercise can have energy deficits and become malnourished if they do not increase their food intake to match their energy needs.”

Boys who exercise too much can become malnourished even when they aren’t restricting their calorie intake, the doctors write. But current treatment guidelines for teen eating disorders don’t offer recommendations on what to do with patients who are exercising excessively.

Teen boys may also engage in what’s known as biohacking, or trying to optimize physiology for muscle building through practices like intermittent fasting, elimination diets, supplements, and multiple cycles of steroid use, the doctors write.

Many supplements that teen boys may use to bulk up are also unregulated, and can include a variety of ingredients that aren’t clearly labeled or approved for human consumption, the doctors add.

Part of the reason teen boys are so hard to diagnose and treat is that very little research on eating disorders focuses on boys and men, said Dr. Trine Tetlie Eik-Nes, a researcher at the Norwegian University of Science and Technology in Trondheim.